package pwd.allen.appender;

import org.apache.log4j.FileAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * DailyMaxRollingFileAppender extends {@link FileAppender} so that the
 * underlying file is rolled over at a user chosen frequency.
 * 
 * <p>
 * The rolling schedule is specified by the <b>DatePattern</b>. This pattern
 * should follow the {@link SimpleDateFormat} conventions. In particular, you
 * <em>must</em> escape literal text within a pair of single quotes. A formatted
 * version of the date pattern is used as the suffix for the rolled file name.
 * 
 * <p>
 * For example, if the <b>File</b> option is set to <code>/foo/bar.log</code>
 * and the <b>DatePattern</b> set to <code>'.'yyyy-MM-dd</code>, on 2001-02-16
 * at midnight, the logging file <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2001-02-16</code> and logging for 2001-02-17 will continue
 * in <code>/foo/bar.log</code> until it rolls over the next day.
 * 
 * <p>
 * Is is possible to specify monthly, weekly, half-daily, daily, hourly, or
 * minutely rollover schedules.
 * 
 * <p>
 * <table border="1" cellpadding="2">
 * <tr>
 * <th>DatePattern</th>
 * <th>Rollover schedule</th>
 * <th>Example</th>
 * 
 * <tr>
 * <td><code>'.'yyyy-MM</code>
 * <td>Rollover at the beginning of each month</td>
 * 
 * <td>At midnight of May 31st, 2002 <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-05</code>. Logging for the month of June will be
 * output to <code>/foo/bar.log</code> until it is also rolled over the next
 * month.
 * 
 * <tr>
 * <td><code>'.'yyyy-ww</code>
 * 
 * <td>Rollover at the first day of each week. The first day of the week depends
 * on the locale.</td>
 * 
 * <td>Assuming the first day of the week is Sunday, on Saturday midnight, June
 * 9th 2002, the file <i>/foo/bar.log</i> will be copied to
 * <i>/foo/bar.log.2002-23</i>. Logging for the 24th week of 2002 will be output
 * to <code>/foo/bar.log</code> until it is rolled over the next week.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd</code>
 * 
 * <td>Rollover at midnight each day.</td>
 * 
 * <td>At midnight, on March 8th, 2002, <code>/foo/bar.log</code> will be copied
 * to <code>/foo/bar.log.2002-03-08</code>. Logging for the 9th day of March
 * will be output to <code>/foo/bar.log</code> until it is rolled over the next
 * day.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-a</code>
 * 
 * <td>Rollover at midnight and midday of each day.</td>
 * 
 * <td>At noon, on March 9th, 2002, <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-03-09-AM</code>. Logging for the afternoon of the 9th
 * will be output to <code>/foo/bar.log</code> until it is rolled over at
 * midnight.
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH</code>
 * 
 * <td>Rollover at the top of every hour.</td>
 * 
 * <td>At approximately 11:00.000 o'clock on March 9th, 2002,
 * <code>/foo/bar.log</code> will be copied to
 * <code>/foo/bar.log.2002-03-09-10</code>. Logging for the 11th hour of the 9th
 * of March will be output to <code>/foo/bar.log</code> until it is rolled over
 * at the beginning of the next hour.
 * 
 * 
 * <tr>
 * <td><code>'.'yyyy-MM-dd-HH-mm</code>
 * 
 * <td>Rollover at the beginning of every minute.</td>
 * 
 * <td>At approximately 11:23,000, on March 9th, 2001, <code>/foo/bar.log</code>
 * will be copied to <code>/foo/bar.log.2001-03-09-10-22</code>. Logging for the
 * minute of 11:23 (9th of March) will be output to <code>/foo/bar.log</code>
 * until it is rolled over the next minute.
 * 
 * </table>
 * 
 * <p>
 * Do not use the colon ":" character in anywhere in the <b>DatePattern</b>
 * option. The text before the colon is interpeted as the protocol specificaion
 * of a URL which is probably not what you want.
 * 
 * <p>
 * You have also to define the maximum number of file are kept before the oldest
 * is erased.
 * </p>
 * 
 * @author Eirik Lygre
 * @author Ceki G&uuml;lc&uuml;
 * @author Riccardo Nicosia;
 */
public class DailyMaxRollingFileAppender extends FileAppender {
	// The code assumes that the following constants are in a increasing
	// sequence.
	static final int TOP_OF_TROUBLE = -1;
	static final int TOP_OF_MINUTE = 0;
	static final int TOP_OF_HOUR = 1;
	static final int HALF_DAY = 2;
	static final int TOP_OF_DAY = 3;
	static final int TOP_OF_WEEK = 4;
	static final int TOP_OF_MONTH = 5;

	/**
	 * The date pattern. By default, the pattern is set to "'.'yyyy-MM-dd"
	 * meaning daily rollover.
	 */
	private String datePattern = "'.'yyyy-MM-dd";

	/**
	 * There is one backup file by default.
	 */
	private int maxBackupIndex = 1;

	/**
	 * The log file will be renamed to the value of the scheduledFilename
	 * variable when the next interval is entered. For example, if the rollover
	 * period is one hour, the log file will be renamed to the value of
	 * "scheduledFilename" at the beginning of the next hour.
	 * 
	 * The precise time when a rollover occurs depends on logging activity.
	 */
	private String scheduledFilename;

	/**
	 * The next time we estimate a rollover should occur.
	 */
	private long nextCheck = System.currentTimeMillis() - 1;

	Date now = new Date();

	SimpleDateFormat sdf;

	RollingPastCalendar rpc = new RollingPastCalendar();

//	int checkPeriod = TOP_OF_TROUBLE;

	// The gmtTimeZone is used only in computeCheckPeriod() method.
	static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");

	/**
	 * The default constructor does nothing.
	 */
	public DailyMaxRollingFileAppender() {
	}

	/**
	 * Instantiate a <code>DailyMaxRollingFileAppender</code> and open the file
	 * designated by <code>filename</code>. The opened filename will become the
	 * ouput destination for this appender.
	 */
	public DailyMaxRollingFileAppender(Layout layout, String filename,
                                       String datePattern) throws IOException {
		super(layout, filename, true);
		this.datePattern = datePattern;
		activateOptions();
	}

	/**
	 * The <b>DatePattern</b> takes a string in the same format as expected by
	 * {@link SimpleDateFormat}. This options determines the rollover schedule.
	 */
	public void setDatePattern(String pattern) {
		datePattern = pattern;
	}

	/** Returns the value of the <b>DatePattern</b> option. */
	public String getDatePattern() {
		return datePattern;
	}

	/**
	 * Set the maximum number of backup files to keep around.
	 * 
	 * <p>
	 * The <b>MaxBackupIndex</b> option determines how many backup files are
	 * kept before the oldest is erased. This option takes a positive integer
	 * value. If set to zero, then there will be no backup files and the log
	 * file will be renamed to the value of the scheduledFilename variable when
	 * the next interval is entered.
	 */
	public void setMaxBackupIndex(int maxBackups) {
		this.maxBackupIndex = maxBackups;
	}

	/**
	 * Returns the value of the <b>MaxBackupIndex</b> option.
	 */
	public int getMaxBackupIndex() {
		return maxBackupIndex;
	}

	@Override
	public void activateOptions() {
		super.activateOptions();

		LogLog.debug("Max backup file kept: " + maxBackupIndex + ".");

		if (datePattern != null && fileName != null) {
			now.setTime(System.currentTimeMillis());
			sdf = new SimpleDateFormat(datePattern);
			int type = computeCheckPeriod();
			printPeriodicity(type);
			rpc.setType(type);
			File file = new File(fileName);
			scheduledFilename = fileName
					+ sdf.format(new Date(file.lastModified()));
		} else {
			LogLog.error("Either File or DatePattern options are not set for appender ["
					+ name + "].");
		}
	}

	void printPeriodicity(int type) {
		switch (type) {
		case TOP_OF_MINUTE:
			LogLog.debug("Appender [[+name+]] to be rolled every minute.");
			break;
		case TOP_OF_HOUR:
			LogLog.debug("Appender [" + name
					+ "] to be rolled on top of every hour.");
			break;
		case HALF_DAY:
			LogLog.debug("Appender [" + name
					+ "] to be rolled at midday and midnight.");
			break;
		case TOP_OF_DAY:
			LogLog.debug("Appender [" + name + "] to be rolled at midnight.");
			break;
		case TOP_OF_WEEK:
			LogLog.debug("Appender [" + name
					+ "] to be rolled at start of week.");
			break;
		case TOP_OF_MONTH:
			LogLog.debug("Appender [" + name
					+ "] to be rolled at start of every month.");
			break;
		default:
			LogLog.warn("Unknown periodicity for appender [[+name+]].");
		}
	}

	// This method computes the roll over period by looping over the
	// periods, starting with the shortest, and stopping when the r0 is
	// different from from r1, where r0 is the epoch formatted according
	// the datePattern (supplied by the user) and r1 is the
	// epoch+nextMillis(i) formatted according to datePattern. All date
	// formatting is done in GMT and not local format because the test
	// logic is based on comparisons relative to 1970-01-01 00:00:00
	// GMT (the epoch).

	int computeCheckPeriod() {
		RollingPastCalendar rollingPastCalendar = new RollingPastCalendar(
				gmtTimeZone, Locale.ENGLISH);
		// set sate to 1970-01-01 00:00:00 GMT
		Date epoch = new Date(0);
		if (datePattern != null) {
			for (int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++) {
				SimpleDateFormat simpleDateFormat = new SimpleDateFormat(
						datePattern);
				simpleDateFormat.setTimeZone(gmtTimeZone); // do all date
															// formatting in GMT
				String r0 = simpleDateFormat.format(epoch);
				rollingPastCalendar.setType(i);
				Date next = new Date(
						rollingPastCalendar.getNextCheckMillis(epoch));
				String r1 = simpleDateFormat.format(next);

				// System.out.println("Type = "+i+", r0 = "+r0+", r1 = "+r1);
				if (r0 != null && r1 != null && !r0.equals(r1)) {
					return i;
				}
			}
		}

		return TOP_OF_TROUBLE; // Deliberately head for trouble...
	}

	/**
	 * Rollover the current file to a new file.
	 */
	void rollOver() throws IOException {
		/* Compute filename, but only if datePattern is specified */
		if (datePattern == null) {
			errorHandler.error("Missing DatePattern option in rollOver().");
			return;
		}

		String datedFilename = fileName + sdf.format(now);
		// It is too early to roll over because we are still within the
		// bounds of the current interval. Rollover will occur once the
		// next interval is reached.
		if (scheduledFilename.equals(datedFilename)) {
			return;
		}

		// close current file, and rename it to datedFilename
		this.closeFile();

		File target = new File(scheduledFilename);
		if (target.exists()) {
			//target.delete();
			target.deleteOnExit();
		}

		File file = new File(fileName);
		boolean result = file.renameTo(target);
		if (result) {
			LogLog.debug(fileName + " -> " + scheduledFilename);

			// If maxBackups <= 0, then there is no file renaming to be done.
			if (maxBackupIndex > 0) {
				// Delete the oldest file, to keep Windows happy.
				file = new File(fileName + dateBefore());

				if (file.exists()){
					//file.delete();
					file.deleteOnExit();
				}
			}
		} else {
			LogLog.error("Failed to rename [[+fileName+]] to [[+scheduledFilename+]].");
		}

		try {
			// This will also close the file. This is OK since multiple
			// close operations are safe.
			this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
		} catch (IOException e) {
			errorHandler.error("setFile(" + fileName + ", false) call failed.");
		}
		scheduledFilename = datedFilename;
	}

	private String dateBefore() {
		String dataAnte = "";

		if (datePattern != null) {
			SimpleDateFormat simpleDateFormat = new SimpleDateFormat(
					datePattern);

			dataAnte = simpleDateFormat.format(new Date(rpc.getPastCheckMillis(
					new Date(), maxBackupIndex)));
		}

		return dataAnte;
	}

	/**
	 * This method differentiates DailyMaxRollingFileAppender from its super class.
	 * 
	 * <p>
	 * Before actually logging, this method will check whether it is time to do
	 * a rollover. If it is, it will schedule the next rollover time and then
	 * rollover.
	 * */
	@Override
	protected void subAppend(LoggingEvent event) {
		long n = System.currentTimeMillis();

		if (n >= nextCheck) {
			now.setTime(n);
			nextCheck = rpc.getNextCheckMillis(now);

			try {
				rollOver();
			} catch (IOException ioe) {
				LogLog.error("rollOver() failed.", ioe);
			}
		}

		super.subAppend(event);
	}

	/*
	 * DEBUG
	 */
	public static void main(String args[]) {
		DailyMaxRollingFileAppender dmrfa = new DailyMaxRollingFileAppender();

		dmrfa.setDatePattern("'.'yyyy-MM-dd-HH-mm");

		dmrfa.setFile("prova");

		System.out.println("dmrfa.getMaxBackupIndex():"
				+ dmrfa.getMaxBackupIndex());

		dmrfa.activateOptions();

		for (int i = 0; i < 5; i++) {
			dmrfa.subAppend(null);

			try {
				Thread.sleep(60000);
			} catch (InterruptedException ex) {
			}

			System.out.println("Fine attesa");
		}
	}
}

/**
 * RollingPastCalendar is a helper class to DailyMaxRollingFileAppender. Given a
 * periodicity type and the current time, it computes the past maxBackupIndex
 * date.
 * */
class RollingPastCalendar extends GregorianCalendar {
	private static final long serialVersionUID = 1L;

	int type = DailyMaxRollingFileAppender.TOP_OF_TROUBLE;

	RollingPastCalendar() {
		super();
	}

	RollingPastCalendar(TimeZone tz, Locale locale) {
		super(tz, locale);
	}

	void setType(int type) {
		this.type = type;
	}

	public long getNextCheckMillis(Date now) {
		return getNextCheckDate(now).getTime();
	}

	public Date getNextCheckDate(Date now) {
		this.setTime(now);

		switch (type) {
			case DailyMaxRollingFileAppender.TOP_OF_MINUTE:
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.MINUTE, 1);
				break;
			case DailyMaxRollingFileAppender.TOP_OF_HOUR:
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.HOUR_OF_DAY, 1);
				break;
			case DailyMaxRollingFileAppender.HALF_DAY:
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				int hour = get(Calendar.HOUR_OF_DAY);
				if (hour < 12) {
					this.set(Calendar.HOUR_OF_DAY, 12);
				} else {
					this.set(Calendar.HOUR_OF_DAY, 0);
					this.add(Calendar.DAY_OF_MONTH, 1);
				}
				break;
			case DailyMaxRollingFileAppender.TOP_OF_DAY:
				this.set(Calendar.HOUR_OF_DAY, 0);
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.DATE, 1);
				break;
			case DailyMaxRollingFileAppender.TOP_OF_WEEK:
				this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
				this.set(Calendar.HOUR_OF_DAY, 0);
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.WEEK_OF_YEAR, 1);
				break;
			case DailyMaxRollingFileAppender.TOP_OF_MONTH:
				this.set(Calendar.DATE, 1);
				this.set(Calendar.HOUR_OF_DAY, 0);
				this.set(Calendar.MINUTE, 0);
				this.set(Calendar.SECOND, 0);
				this.set(Calendar.MILLISECOND, 0);
				this.add(Calendar.MONTH, 1);
				break;
			default:
				throw new IllegalStateException("Unknown periodicity type.");
		}
		return getTime();
	}

	public long getPastCheckMillis(Date now, int maxBackupIndex) {
		return getPastDate(now, maxBackupIndex).getTime();
	}

	public Date getPastDate(Date now, int maxBackupIndex) {
		this.setTime(now);

		switch (type) {
		case DailyMaxRollingFileAppender.TOP_OF_MINUTE:
			this.set(Calendar.SECOND, this.get(Calendar.SECOND));
			this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
			this.set(Calendar.MINUTE, this.get(Calendar.MINUTE)
					- maxBackupIndex);
			break;

		case DailyMaxRollingFileAppender.TOP_OF_HOUR:
			this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
			this.set(Calendar.SECOND, this.get(Calendar.SECOND));
			this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
			this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY)
					- maxBackupIndex);
			break;

		case DailyMaxRollingFileAppender.HALF_DAY:
			this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
			this.set(Calendar.SECOND, this.get(Calendar.SECOND));
			this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
			int hour = get(Calendar.HOUR_OF_DAY);
			if (hour < 12) {
				this.set(Calendar.HOUR_OF_DAY, 12);
			} else {
				this.set(Calendar.HOUR_OF_DAY, 0);
			}
			this.set(Calendar.DAY_OF_MONTH, this.get(Calendar.DAY_OF_MONTH)
					- maxBackupIndex);

			break;

		case DailyMaxRollingFileAppender.TOP_OF_DAY:
			this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY));
			this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
			this.set(Calendar.SECOND, this.get(Calendar.SECOND));
			this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
			this.set(Calendar.DATE, this.get(Calendar.DATE) - maxBackupIndex);
			break;

		case DailyMaxRollingFileAppender.TOP_OF_WEEK:
			this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
			this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY));
			this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
			this.set(Calendar.SECOND, this.get(Calendar.SECOND));
			this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
			this.set(Calendar.WEEK_OF_YEAR, this.get(Calendar.WEEK_OF_YEAR)
					- maxBackupIndex);
			break;

		case DailyMaxRollingFileAppender.TOP_OF_MONTH:
			this.set(Calendar.DATE, this.get(Calendar.DATE));
			this.set(Calendar.HOUR_OF_DAY, this.get(Calendar.HOUR_OF_DAY));
			this.set(Calendar.MINUTE, this.get(Calendar.MINUTE));
			this.set(Calendar.SECOND, this.get(Calendar.SECOND));
			this.set(Calendar.MILLISECOND, this.get(Calendar.MILLISECOND));
			this.set(Calendar.MONTH, this.get(Calendar.MONTH) - maxBackupIndex);
			break;

		default:
			throw new IllegalStateException("Unknown periodicity type.");
		}

		return getTime();
	}
}